The Lord didn’t speak these words to Noah; He spoke them to Himself in His own heart. It was His gracious response to Noah’s faith, obedience, and worship. What did God promise?
The ground cursed no more (v. 21a). God had cursed the ground because of Adam’s sin (3:17) and had added a further curse because of Cain’s sins (4:11–12). God’s promise recorded here didn’t invalidate either of those curses, and they won’t be removed until Jesus returns and God’s people dwell in the Holy City (Rev. 22:3). But in His grace, God decided not to add to man’s affliction.
No more universal floods (v. 21b). God also determined that there would be no future floods. God’s reason given in verse 21 has been variously explained, and your explanation depends to some degree on your translation of the text. Did God say “for the imagination of man’s heart is evil” (kjv, niv margin), or did He say “even though every inclination of his heart is evil” (niv)? The Lord had originally sent the flood because of the evil hearts of the people (6:5), so not to send another judgment would make it look like the flood was a mistake or a failure, or that God had given up on the human race created in His own image.
If we translate 8: “for,” then we have God saying, “The human heart is incurably wicked. The flood wiped out the transgressors, but it couldn’t change hearts. Therefore, to have another judgment won’t solve the problem.” If we translate it “even though,” then we have God saying: “Yes, they deserve judgment because their hearts are wicked. And to persist in sin and not learn their lesson from this flood only shows how evil they are. But in grace, I will not send another flood or curse the ground.”
Perhaps both are true. The important thing is that God spoke these words in response to Noah’s sacrifice, and that the sacrifice was a picture of the sacrifice of Christ (Heb. 10:1–10; Eph. 5:2). On the basis of the atonement accomplished by Jesus Christ on the cross, God could say, “A price has been paid for the sins of the world, and I can withhold judgment. Justice has been met, My law has been upheld, and I can show grace to a lost world. I will not send another flood and wipe out the human race. Instead, I will offer them My great salvation.”
This doesn’t mean that God doesn’t judge sin today or that there will be no future judgment of the world. Romans 1:18ff. makes it clear that God’s judgment is being revealed against sinners right now through the consequences of their sins. God gave them over to their own sinful bondage and gave them up to the consequences of their sins in their own bodies. One of the greatest judgments God can send to sinners is to let them have their own way and then pay for it in their own lives. That’s the judgment the world is experiencing right now. There will be a future global judgment, but not a judgment of water; it will be a judgment of fire (2 Peter 3).
No interruption of the cycle of nature (v. 22). The flood had interrupted the normal cycle of the seasons for a year, but that would never be repeated. Instead, God reaffirmed that the rhythm of days and weeks and seasons would continue as long as the earth endured. Without this guarantee, mankind could never be sure of having the necessities of life.
We know now that the steady cycle of days and nights, weeks and months, seasons and years, is maintained by the rotation of the earth on its axis and the orbit of the earth around the sun. God made it that way so that His universe would operate effectively. Although there were myriads of galaxies to choose from, the Lord chose to pour His love and grace down upon the inhabitants of the earth. “The earth is the Lord’s” (Ps. 24:1). The Lord so arranged the universe that the living things on earth might be maintained, and this includes men and women who too often forget God’s care.
The guarantee in Genesis 8: gives us hope and courage as we face an unknown future. Each time we go to bed for the night, or turn the calendar to a new month, we should be reminded that God is concerned about planet earth and its inhabitants. With the invention of the electric light and modern means of transportation and communication, our world has moved away from living by the cycles of nature established by God. We no longer go to bed at sundown and get up at sunrise, and if we don’t like the weather where we are, we can quickly travel to a different climate. But if God were to dim the sun, rearrange the seasons, or tilt the earth at a different angle, our lives would be in jeopardy.
God invites us to live a day at a time. Jesus taught us to pray, “Give us this day our daily bread” (Matt. 6:11) and to be thankful for it. “As your days, so shall your strength be” (Deut. 33: nkjv; see Matt. 6:25–34). When His disciples warned Jesus not to go to Bethany, He replied, “Are there not twelve hours in the day?” (John 11:9). He obeyed the Father’s schedule and lived a day at a time, trusting the Father to care for Him.
God’s “covenant of day and night” is especially meaningful to the people of Israel, for it guarantees them His care and protection so that they will never cease to be a nation (Jer. 33:19–26). God’s promise that He will not send another flood is assurance to the Jews that His covenant with them will never be broken (Isa. 54:7–10).
We’re prone to take for granted sunrise and sunset, the changing face of the moon and the changing seasons, but all of these functions are but evidences that God is on the throne and keeping His promises. All creation preaches a constant sermon, day after day, season after season, that assures us of God’s loving care. We can trust His Word, for “there has not failed one word of all his good promise” (1 Kings 8:56).